You have to change it at your registrar (namespro) and , once changed there, login to CIRA to approve the change.
(Namespro has 2 areas of change - one is for your account with them, and the other is your CIRA profile.)
If you do NOT want your telephone to be public, have at least 1 domain at 10dollar, as they have the complete number of fields in the CIRA profile. You can then enter your telephone number in the "Other telephone" field, which meets CIRA's requirements, but conceals your phone number even if you have public whois.
(I don't know why namespro doesn't have this field)